\begin{table}%t1
%%\centering
\par
\caption{Wavelenght ($\lambda$ in $\AA$) for the  $\rm 3p_{1/2}-3p_{3/2}$ spectral line in the aluminium sequence. \label{tab1} }
\begin{tabular}{rrrrrr} 
\hline\hline
 $Z$ & $ \lambda^a$ & $\lambda^b$ & $Z$ & $ \lambda^a$ & $\lambda^b$\\
\par
\cline{1-6}
21 & 17369.592 & 17095.820 & 51 & 198.848 & 196.825 \\
22&13266.334&13140.749&52&181.887&179.708\\
23&10320.540&10266.303&53&166.691&164.373\\
24&8161.484&8137.911&54&153.045&150.604\\
25&6542.527&6534.657&55&140.762&138.212\\
26&5308.476&5308.261&56&129.684&127.038\\
27&4353.431&4357.040&57&119.672&116.942\\
28&3604.572&3609.913&58&110.604&107.802\\
29&3005.676&3016.376&59&102.377&99.512\\
30&2534.457&2539.926&60&94.899&91.981\\
31&2148.857&2153.855&61&88.089&85.127\\
32&1833.956&1838.301&62&81.878&78.879\\
33&1574.163&1578.329&63&76.204&73.174\\
34&1358.880&1362.578&64&71.011&67.958\\
35&1179.739&1182.312&65&66.252&63.182\\
36&1027.708&1030.743&66&61.884&58.802\\
37&900.103&902.559&67&57.869&54.780\\
38&791.571&793.567&68&54.174&51.081\\
39&698.865&700.411&69&50.769&47.677\\
40&619.301&620.415&70&47.626&44.538\\
41&550.707&551.411&71&44.723&41.642\\
42&491.321&491.646&72&42.036&38.966\\
43&439.703&439.671&73&39.548&36.491\\
44&394.666&394.303&74&37.241&34.199\\
45&355.231&354.561&75&35.110&32.074\\
46&320.585&319.633&76&33.110&30.103\\
47&290.047&288.838&77&31.258&28.272\\
48&263.049&261.606&78&29.535&26.570\\
49&239.110&237.454&79&27.461&24.986\\
50&217.824&215.975&80&26.428&23.511\\
\cline{1-6} 
\\[-3mm]
\multicolumn{6}{l}{${}^a$ This work.} 
\\
\multicolumn{6}{l}{${}^{b}$ Huang 1986.}
\end{tabular}
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\end{table}